Conventionally, a vibratory feeder, a screw feeder, a table feeder, a rotary feeder, etc., are used for a device for supplying powdery additives to raw liquid materials. For example, as disclosed in Japanese Patent Laid-open Publication No. 2001-55588, such a device is located on a tank that stores raw liquid material and has an agitator so that the supplied powdery additives and the raw liquid materials are dispersed by the agitator.
However, since the powdery additives that are discharged from the device to the tank freely fall to the surface of the liquid by means of gravity, they scatter in the tank while they fall, to then adhere on the inner face of the tank. This is a problem. When the powdery additives fall to the surface of the liquid, droplets spread so that the powdery additives or raw liquid materials adhere to the inner face of the tank. Thus problems arise where the ratio of the blend of a product (a mixture of the raw liquid materials and the powdery additives) varies and where removing fixed objects becomes difficult after the raw liquid materials and the powdery additives that adhere to the inner face dry and become hard on the face.
Further, if the powdery additives are fine powder, they may drift on the surface of the liquid without mixing with the liquid, or may agglutinate. Thus problems arise where no dispersion can be achieved or a piping or a discharging port is clogged. A countermeasure may be to generate a flow in the liquid to encourage dispersion of the powdery additives in the liquid. But this countermeasure is unusable for a liquid that has a high viscosity. Further, if the viscosity is high, it is also a problem that a long time is needed to expel air from the mixture after the dispersing process. For powdery additives that contain much air, since the bulk density of them is low, the rate for supplying them cannot be increased. This is also a problem.